With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cbgpRouteAggregatorAS
CISCO BGP4 Route Aggregator AS
1.3.6.1.4.1.9.9.187.1.1.1.1.15
The AS number of the last BGP4 speaker that performed route aggregation. A value of zero (0) indicates the absence of this attribute.
Back to CISCO-BGP4-MIB MIB page.
IPHost Network monitor allows you to monitor cbgpRouteAggregatorAS on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco firewalls right now.